diff -drupN a/drivers/md/dm-android-verity.h b/drivers/md/dm-android-verity.h
--- a/drivers/md/dm-android-verity.h	1970-01-01 03:00:00.000000000 +0300
+++ b/drivers/md/dm-android-verity.h	2022-06-12 05:28:14.000000000 +0300
@@ -0,0 +1,123 @@
+/*
+ * Copyright (C) 2015 Google, Inc.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#ifndef DM_ANDROID_VERITY_H
+#define DM_ANDROID_VERITY_H
+
+#include <crypto/sha.h>
+
+#define RSANUMBYTES 256
+#define VERITY_METADATA_MAGIC_NUMBER 0xb001b001
+#define VERITY_METADATA_MAGIC_DISABLE 0x46464f56
+#define VERITY_METADATA_VERSION 0
+#define VERITY_STATE_DISABLE 1
+#define DATA_BLOCK_SIZE (4 * 1024)
+#define VERITY_METADATA_SIZE (8 * DATA_BLOCK_SIZE)
+#define VERITY_TABLE_ARGS 10
+#define VERITY_COMMANDLINE_PARAM_LENGTH 20
+#define BUILD_VARIANT 20
+
+/*
+ * <subject>:<sha1-id> is the format for the identifier.
+ * subject can either be the Common Name(CN) + Organization Name(O) or
+ * just the CN if the it is prefixed with O
+ * From https://tools.ietf.org/html/rfc5280#appendix-A
+ * ub-organization-name-length INTEGER ::= 64
+ * ub-common-name-length INTEGER ::= 64
+ *
+ * http://lxr.free-electrons.com/source/crypto/asymmetric_keys/x509_cert_parser.c?v=3.9#L278
+ * ctx->o_size + 2 + ctx->cn_size + 1
+ * + 41 characters for ":" and sha1 id
+ * 64 + 2 + 64 + 1 + 1 + 40 (172)
+ * setting VERITY_DEFAULT_KEY_ID_LENGTH to 200 characters.
+ */
+#define VERITY_DEFAULT_KEY_ID_LENGTH 200
+
+#define FEC_MAGIC 0xFECFECFE
+#define FEC_BLOCK_SIZE (4 * 1024)
+#define FEC_VERSION 0
+#define FEC_RSM 255
+#define FEC_ARG_LENGTH 300
+
+#define VERITY_TABLE_OPT_RESTART "restart_on_corruption"
+#define VERITY_TABLE_OPT_LOGGING "ignore_corruption"
+#define VERITY_TABLE_OPT_IGNZERO "ignore_zero_blocks"
+
+#define VERITY_TABLE_OPT_FEC_FORMAT \
+	"use_fec_from_device %s fec_start %llu fec_blocks %llu fec_roots %u ignore_zero_blocks"
+#define VERITY_TABLE_OPT_FEC_ARGS 9
+
+#define VERITY_DEBUG 0
+
+#define DM_MSG_PREFIX                   "android-verity"
+
+#define DM_LINEAR_ARGS 2
+#define DM_LINEAR_TARGET_OFFSET "0"
+
+/*
+ * There can be two formats.
+ * if fec is present
+ * <data_blocks> <verity_tree> <verity_metdata_32K><fec_data><fec_data_4K>
+ * if fec is not present
+ * <data_blocks> <verity_tree> <verity_metdata_32K>
+ */
+struct fec_header {
+	__le32 magic;
+	__le32 version;
+	__le32 size;
+	__le32 roots;
+	__le32 fec_size;
+	__le64 inp_size;
+	u8 hash[SHA256_DIGEST_SIZE];
+} __attribute__((packed));
+
+struct android_metadata_header {
+	__le32 magic_number;
+	__le32 protocol_version;
+	char signature[RSANUMBYTES];
+	__le32 table_length;
+};
+
+struct android_metadata {
+	struct android_metadata_header *header;
+	char *verity_table;
+};
+
+struct fec_ecc_metadata {
+	bool valid;
+	u32 roots;
+	u64 blocks;
+	u64 rounds;
+	u64 start;
+};
+
+struct bio_read {
+	struct page **page_io;
+	int number_of_pages;
+};
+
+extern struct target_type linear_target;
+
+extern void dm_linear_dtr(struct dm_target *ti);
+extern int dm_linear_map(struct dm_target *ti, struct bio *bio);
+extern void dm_linear_status(struct dm_target *ti, status_type_t type,
+			unsigned status_flags, char *result, unsigned maxlen);
+extern int dm_linear_prepare_ioctl(struct dm_target *ti,
+                struct block_device **bdev, fmode_t *mode);
+extern int dm_linear_iterate_devices(struct dm_target *ti,
+			iterate_devices_callout_fn fn, void *data);
+extern int dm_linear_ctr(struct dm_target *ti, unsigned int argc, char **argv);
+extern long dm_linear_direct_access(struct dm_target *ti, sector_t sector,
+                                 void **kaddr, pfn_t *pfn, long size);
+#endif /* DM_ANDROID_VERITY_H */